Do you use slate for food, and how do you care for it? I have some slate cheese plates that I use at demos, writing flavors on them. A chef I know recommended rubbing them with oil, but I was concerned that would affect being able to write on them with the chalk (or soapstone or whatever it is that they include for writing), and I was just looking at some photos on Instagram where the slate looks lustrous like it may have been oiled. So far I've been using a damp towel to clean them - they have felt on the bottoms so can't be submerged. If there is a better way, enlighten me!